The flood of Chinese money into the city before the mainland’s National Day celebrations in early October has slowed to a trickle since traders returned from the week-long break.
Investors in Shanghai spent more than $8 billion on Hong Kong shares in September, the biggest monthly inflow through the exchange link since it began in 2014.
Net buying this month has been just 7 percent of that amount, data compiled by Bloomberg show.
The narrowing valuation discount on the city’s dual-listed shares and concern about the Federal Reserve’s impending rate increase may have spurred mainland investors to turn off the taps, according to Hong Kong analysts.